Provision of public service identities

ABSTRACT

A mechanism to handle Public Service Identities identifying services in a network when a given Public Service Identity (PSI) belongs to a range of Public Service Identities defined as a ‘Wildcard PSI’ range. An enhanced Home Subscriber Server, serving entity, and routing entity, all co-operating to carry out the invention by handling an identifier of the ‘Wildcard PSI’ range, which includes the given Public Service Identity, the ‘Wildcard PSI’ range being associated with a common service profile to be applied for services identified by those Public Service Identities belonging to the ‘Wildcard PSI’ range.

FIELD OF THE INVENTION

The present invention generally relates to invocation of services thatare identified by respective Public Service Identities. In particular,the present invention relates to the routing of Public ServiceIdentities that belong to a range of Public Service Identities held as aso-called ‘Wildcard PSI’, the range sharing a service profile.

BACKGROUND

At present, the 3^(rd) Generation Partnership Project (generally knownas ‘3GPP’) has introduced the basis for an IP Multimedia Subsystem(generally known as ‘IMS’) and IMS services, as stated in the technicalspecification 3GPP TS 23.228 V6.9.0. In accordance with 3GPP, PublicService Identities are different from Public User Identities in therespect that the former identify services, which may be hosted andoperated by application servers (generally known as ‘AS’ in at leastsaid 3GPP technical specification), whereas the latter identify userswhose subscription data are hosted in subscriber databases under networkoperator premises, and who are served by different serving network nodessuch as a Serving Call Session Control Function (known as ‘S-CSCF’ under3GPP). A definition of the terms ‘Service’ and ‘user’, as usedthroughout this specification can be found in 3GPP TS 21.905:“Vocabulary for 3GPP Specifications”.

Generally speaking, Public Service Identities are used to identifyservices running on specific application servers. In particular, PublicService Identities are used to identify groups of services such as achat-type service, for instance, that may use a Public Service Identity(hereinafter referred to as ‘PSI’) to which the users may establish asession in order to enable the sending and reception of messages fromother session participants. Public Service Identities are presentlyassumed to take the form of SIP URL or SIP URI as defined by theInternet Engineering Task Forces (IETF) in RFC 3261 and RFC 2396, aswell as in the so-called ‘tel:’-URI format as defined in RFC 3966. Anexemplary Public Service Identity (PSI) identifying a chat-type servicemay be sip:chatlist_X@example.com.

Public User Identities can adopt two different forms of representationand scope. A first one is a so-called ‘Distinct PSI’, such assip:my_service@example.com, and determines an individual Public ServiceIdentity representing a unique service and which can be individuallyinvoked. A second scope and form of representation is a so-called‘Wildcard PSI’, such as sip:chatlist_*@example.com may be, wherein arange of Public User Identities is defined with a same domain part inthe SIP URI and with a wildcard indication in the user part of the SIPURI. An interested reader may find definitions for ‘Distinct PSI’ and‘Wildcard PSI’ through the technical specification 3GPP TS 23.003.

In this respect, an individual Public Service Identity might have beendefined independently as a ‘Distinct PSI’, or might have been definedwithin a ‘Wildcard PSI’ range, which implicitly includes a plurality ofPublic Service Identities within the range.

In operation, the IMS provides the means for routing IMS messagesrelated to particular IMS services by using corresponding Public ServiceIdentities.

Therefore, Public Service Identities are stored in a Home SubscriberServer (generally known as ‘HSS’ under 3GPP specifications) holdingsubscription data for subscribers of a home network operator. A servicemay be invoked by a user accessing IMS through a Proxy Call SessionControl Function (known as ‘P-CSCF’ under 3GPP) by using a given PublicService Identity. This invocation is received at a routing entity of thehome network, preferably an Interrogating Call Session Control Function(known as ‘I-CSCF’ under 3GPP), which interrogates the HSS about thegiven Public Service Identity. The HSS checks whether the given PublicService Identity is defined in the HSS in order to find an S-CSCFalready assigned for handling the given Public Service Identity, or anapplication server where the corresponding service runs if the networkis configured for such direct invocation, or server capabilitiesrequired for selecting an S-CSCF if such serving entity is not assignedyet for the given Public Service Identity.

If no S-CSCF was already assigned at the HSS for handling the givenPublic Service Identity, the server capabilities received at the I-CSCFare used to select an appropriate S-CSCF for handling the service. Theservice invocation with the given Public Service Identity is forwardedto the selected S-CSCF, which informs the HSS in order to be assignedtherein as currently serving the given Public Service Identity. As forthe previous interrogation, the HSS checks whether the given PublicService Identity is defined in the HSS in order to mark the assignedS-CSCF, and in order to fetch an applicable service profile for thegiven Public Service Identity to be returned towards the S-CSCF.

This service profile includes an identifier of the Application Serverwhere the corresponding service is executed so that, once the applicableservice profile for the given Public Service Identity is obtained at theS-CSCF, the S-CSCF may forward the invocation of the service towards theApplication Server indicated in the service profile. The ApplicationServer (generally abbreviated as “AS”) then checks whether the givenPublic Service Identity is defined and fetches the logic to be executedfor the given Public Service Identity.

With the currently existing mechanism, the routing of an invocation ofservice identified by a Public Service Identity includes at least twochecking procedures in the HSS in order to match the given PublicService Identity with those Public Service Identities defined in theHSS, and one checking procedure in the AS in order to fetch the servicelogic associated with the given Public Service Identity. These checkingprocedures may become more complex than expected as trying to match thegiven Public Service Identity against all the individually definedPublic Service Identities and against those Public Service Identitiesimplicitly defined within a so-called ‘Wildcard PSI’ range.

These three checking procedures are increased to, at least, fourchecking procedures in networks where more than one HSS exists since,prior to interrogate an HSS about a Public Service Identity, the routingentity should firstly interrogate a central entity in the network aboutthe Public Service Identity in order to obtain an identifier of the HSSholding such Public Service Identity. In such scenario with more thanone HSS, Public Service Identities might have been defined in any HSS ofthe network, individually as a ‘Distinct PSI’ or within a ‘Wildcard PSI’range, and a checking procedure is required at least four times in orderto identify relevant data to apply for a given Public Service Identity.

Moreover, each service profile received for a given Public ServiceIdentity at the S-CSCF is stored therein so that further invocationswith respective Public Service Identities may not require download of aservice profile if a service profile were already stored for each PublicService Identity.

SUMMARY OF THE INVENTION

The present invention is aimed to simplify this mechanism in such amanner that the needs for checking procedures in different networkentities, and the needs for storage of service profiles in every S-CSCF,are minimized. In particular, the present invention is aimed to providea simplified mechanism to handle Public Service Identities identifyingservices in a network when a given Public Service Identity (PSI) belongsto a range of Public Service Identities defined as a so-called ‘WildcardPSI’ range.

Therefore, the present invention provides a new method, a new centralentity in the network, and enhanced Home Subscriber Server, servingentity and routing entity, all co-operating to carry out differentembodiments for the invention.

In accordance with a first aspect of the present invention, there isprovided a central entity for handling Public Service Identities in anetwork with several Home Subscriber Servers, wherein a Public ServiceIdentity identifies a service and is held by a Home Subscriber Server.This central entity comprises to this end:

-   -   means for associating a Public Service Identity with an        identifier of the Home Subscriber Server holding the Public        Service Identity;    -   means for answering a routing query based on a given Public        Service Identity with the identifier of the Home Subscriber        Server holding the Public Service Identity;    -   means for distinguishing whether the given Public Service        Identity is held as a ‘Distinct PSI’, or the Public Service        Identity belongs to a range of Public Service Identities held as        a ‘Wildcard PSI’; and    -   means for answering the routing query also with the identifier        of the ‘Wildcard PSI’, which the Public Service Identity belongs        to.

This central entity may advantageously include means for associatingwith the Public Service Identity an identifier of an application serverexecuting the service identified by the Public Service Identity.Moreover, the central entity may as well include means for instructingthe Home Subscriber Server to associate the Public Service Identity withthe identifier of the application server executing the service.

On the other hand, the central entity may be designed in such mannerthat the Home Subscriber Server assigned to hold an individual PublicService Identity is the Home Subscriber Server assigned to hold a‘Wildcard PSI’ range that includes the individual Public ServiceIdentity.

A dedicated device may be provided to act as this central entity inaccordance with the invention, or other different network entities maybe arranged for this purpose. For example, this central entity may bealso arranged for carrying out a subscription locator function and, tothis end, the central entity may have means for answering a routingquery for a given Public User Identity with an identifier of a HomeSubscriber Server holding the subscription for the corresponding user.

In accordance with a second aspect of the present invention, there isprovided a Home Subscriber Server for holding Public Service Identitiesin a network, wherein each Public Service Identity identifying a servicecan be assigned to a serving entity. Therefore, the Home SubscriberServer comprises:

-   -   means for responding a routing query from a routing entity, the        routing query based on a given Public Service Identity, either        with an identifier of a serving entity already assigned for the        Public Service Identity, or with capabilities required for        selecting the serving entity;    -   means for distinguishing whether the given Public Service        Identity is held as a ‘Distinct PSI’, or the given Public        Service Identity belongs to a range of Public Service Identities        held as a ‘Wildcard PSI’; and    -   means for including in the response to the routing query an        identifier of the ‘Wildcard PSI’ range, which the given Public        Service Identity belongs to.

This Home Subscriber Server may also include:

-   -   means for associating each individual Public Service Identity        held as a ‘Distinct PSI’ with a particular service profile for        executing the service; and    -   means for associating a range of Public Service Identities held        as a ‘Wildcard PSI’ with a common service profile applicable for        any Public Service Identity belonging to the ‘Wildcard PSI’.

Moreover, regarding the handling of the above particular and commonservice profiles, the Home Subscriber Server may further include:

-   -   means for providing the particular service profile upon a query        with the individual Public Service Identity held as a ‘Distinct        PSI’, or upon any change of contents in the particular service        profile; and    -   means for providing the common service profile upon a query with        any Public Service Identity belonging to the ‘Wildcard PSI’, or        upon any change of contents in the common service profile.

Additional advantages may be obtained regarding the distribution ofPublic Service Identities between different Home Subscriber Servers withhelp of the above central entity if the Home Subscriber Server isprovided with means for receiving a routing query from a routing entity,the routing query based on a first ‘Wildcard PSI’ which is a sub-rangeof a second ‘Wildcard PSI’ as defined in the Home Subscriber Server.Moreover, an easier implementation may be achieved by having in the HomeSubscriber Server means for assigning a serving entity for handlingPublic Service Identities included in a ‘Wildcard PSI’ range uponreceipt of an indication from the serving entity of being currentlyholding the ‘Wildcard PSI’ range.

In accordance with a third aspect of the present invention, there isprovided a serving entity assignable for handling a service identifiedby a Public Service Identity. Therefore, this serving entity comprises:

-   -   means for receiving an invocation of a service identified by a        given Public Service Identity;    -   means for receiving with the invocation an identifier of a        ‘Wildcard PSI’ range which the given Public Service Identity        belongs to; and    -   means for informing to a Home Subscriber Server holding Public        Service Identities in a network of being the serving entity        currently holding the ‘Wildcard PSI’ range.

This serving entity may advantageously comprise means for determiningwhether a service profile is already available for the given PublicService Identity, or a common service profile is already available forthe ‘Wildcard PSI’ range, so that unnecessary download are minimized.

Nevertheless, the serving entity may be enhanced to further comprisemeans for obtaining from a Home Subscriber Server a common serviceprofile associated with the ‘Wildcard PSI’ range.

Moreover, and especially applicable for services running in an externalApplication Server, the serving entity may also comprise means forforwarding the received service invocation towards an Application Serverfor executing the service identified by the given Public ServiceIdentity, the invocation including the identifier of the ‘Wildcard PSI’range which the given Public Service Identity belongs to.

Particularly applicable to an IMS network, as presently described under3GPP specifications, this serving entity may be a Serving Call SessionControl Function.

In accordance with a fourth aspect of the present invention, there isprovided a routing entity for routing an invocation of a serviceidentified by a Public Service Identity in a network towards a servingentity assignable for handling the service. Therefore, the routingentity comprises:

-   -   means for receiving an invocation of a service identified by a        given Public Service Identity;    -   means for obtaining from a Home Subscriber Server holding the        given Public Service Identity either an identifier of a serving        entity already assigned for the given Public Service Identity,        or capabilities required for selecting a serving entity;    -   means for forwarding the received invocation of service towards        a selectable serving entity;    -   means for receiving, from a network entity holding the given        Public Service Identity, an identifier of a ‘Wildcard PSI’ range        which the given Public Service Identity belongs to; and    -   means for including in the invocation forwarded towards the        serving entity the identifier of the ‘Wildcard PSI’ range, which        the Public Service Identity belongs to.

Particularly interesting for networks with more than one Home SubscriberServer, the routing entity may be such that the means for receiving anidentifier of a ‘Wildcard PSI’ range also includes means for obtainingfrom a central entity an identifier of the Home Subscriber Serverholding the given Public Service Identity.

This routing entity may be such that comprises means for receiving fromthe central entity a ‘Wildcard PSI’ range. Moreover, the routing entitymay further comprise means for interrogating the Home Subscriber Serverabout a serving entity assignable for the indicated ‘Wildcard PSI’range, received from the central entity and which the Public ServiceIdentity belongs to.

In this respect, the identifier of the ‘Wildcard PSI’ range to beincluded in the invocation forwarded by this routing entity is the onereceived from the Home Subscriber Server.

Additional advantages may be still obtained if the means included at therouting entity for sending a routing a query towards the Home SubscriberServer includes means for obtaining from the above central entity anidentifier of the Home Subscriber Server holding the Public ServiceIdentity.

Particularly applicable to an IMS network, as presently described under3GPP specifications, this routing entity may preferably be anInterrogating Call Session Control Function.

Apart from the co-operating entities cited above to achieve the objectsof the invention, there is also provided in accordance with a fifthaspect of the invention a method for invoking a service identified by aPublic Service Identity in a network, the service being handled by aserving entity and the Public Service Identity being held at a HomeSubscriber Server. This method comprises the steps of:

-   -   receiving an invocation of a service identified by a given        Public Service Identity at a routing entity;    -   interrogating a Home Subscriber Server holding the given Public        Service Identity about a serving entity assignable for handling        the given Public Service Identity;    -   forwarding the received invocation of service towards the        assignable serving entity;    -   answering the interrogation with an identifier of a ‘Wildcard        PSI’ range which the given Public Service Identity belongs to;    -   forwarding the identifier of the ‘Wildcard PSI’ range towards        the assignable serving entity; and    -   assigning a common service profile to the ‘Wildcard PSI’ to be        applicable for Public Service Identities included in the        ‘Wildcard PSI’ range.

Particularly interesting for networks with more than one Home SubscriberServer, the method may further comprise a step of interrogating acentral entity about the Home Subscriber Server holding the given PublicService Identity; and a step of receiving an identifier of the HomeSubscriber Server. Moreover, this method may also comprise a step ofreceiving from the central entity an identifier of a first ‘WildcardPSI’ range, which the given Public Service Identity belongs to.

Aligned with advantageous embodiments for the above entities, the stepof interrogating a Home Subscriber Server about a serving entity, inthis method, may comprise a step of forwarding the identifier of a first‘Wildcard PSI’ range received from the central entity. In this case, thestep of answering the interrogation with an identifier of a ‘WildcardPSI’ range may include a step of matching the first ‘Wildcard PSI’ as asub-range of a second ‘Wildcard PSI’ to be returned with the answer.

BRIEF DESCRIPTION OF DRAWINGS

The features, objects and advantages of the invention will becomeapparent by reading this description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with only one HSS in accordance with a first embodiment of theinvention.

FIG. 2 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with more than one HSS in accordance with a first embodiment ofthe invention.

FIG. 3 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with only one HSS in accordance with a second embodiment of theinvention.

FIG. 4 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with more than one HSS in accordance with a second embodiment ofthe invention.

FIG. 5 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with more than one HSS in accordance with a third embodiment ofthe invention.

FIG. 6 illustrates a basic signalling flow describing how a given PublicService Identity belonging to a ‘Wildcard PSI’ range may be treated in anetwork with more than one HSS in accordance with a fourth embodiment ofthe invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following describes some preferred embodiments for providing asimplified mechanism for handling Public Service Identities that aredefined in a Home Subscriber Server within respective ‘Wildcard PSI’ranges. For the purpose of the present invention a ‘Wildcard PSI’ rangemay adopt, among others, any of the following formats: Range*; *Range;and Range1*Range2.

In accordance with a first embodiment illustrated in FIG. 1 whereinthere is a unique Home Subscriber Server (HSS) in the IMS network, arouting entity such as an Interrogating Call Session Control Function(I-CSCF) defined under 3GPP receives (S-10) a service invocation(INVITE) addressing a given Public Service Identity (PSI-id). Therouting entity (I-CSCF) interrogates (S-13) the HSS preferably with aLocation Info Request (LIR) that includes the given Public ServiceIdentity (PSI-id). Under this embodiment relevant for the purpose of thepresent invention, the HSS finds that this given Public Service Identity(PSI-id) is not defined as a ‘Distinct PSI’ but matches a ‘WildcardPSI’. The HSS also finds that this ‘Wildcard PSI’ has not being assignedyet any S-CSCF.

The HSS then returns back (S-20) to the interrogating and routing entity(I-CSCF) server capabilities required to select an appropriate servingentity (S-CSCF) and includes in accordance with the invention the‘Wildcard PSI’, which the given Public Service Identity (PSI-id) belongsto. The server capabilities and the ‘Wildcard PSI’ may be preferablysent in a Location Info Answer (LIA). The routing entity (I-CSCF)selects an appropriate serving entity (S-CSCF) harmonizing with thereceived server capabilities, and forwards (S-21) the service invocation(INVITE) to the selected serving entity (S-CSCF), and including thereceived ‘Wildcard PSI’ along with the given Public Service Identity(PSI-id).

The selected serving entity (S-CSCF) receiving the service invocationinforms (S-22) about its selection to the HSS, preferably with a ServerAssignment Request (SAR), and including the received ‘Wildcard PSI’instead of, or along with, the given Public Service Identity (PSI-id).

In accordance with an aspect of the present invention the HSS has each‘Wildcard PSI’ associated with a common service profile applicable toall individual Public Service Identities that belong to, or are includedin, said ‘Wildcard PSI’. Consequently, the HSS assigns an identifier(S-CSCF-id) of the serving entity (S-CSCF), which is currently handlingnot only the given Public Service Identity but also all Public ServiceIdentities belonging to the ‘Wildcard PSI’, to said ‘Wildcard PSI’.Then, the HSS returns back (S-17) to the serving entity (S-CSCF) thecommon service profile associated to the ‘Wildcard PSI’, preferably witha Service Assignment Answer (SAA).

The serving entity (S-CSCF) receiving the common service profile storesit in association with the ‘Wildcard PSI’ for further applicableinvocations; it gets, among the service data included in the serviceprofile, an identifier of an Application Server (AS) where a serviceidentified by the given Public Service Identity (PSI-id) is executed;and it eventually forwards (S-23) the service invocation (INVITE) tosaid Application Server (AS) including the received ‘Wildcard PSI’.

The Application Server (AS) receiving the ‘Wildcard PSI’ may, underparticular criteria and implementation options, apply unique servicelogic for all Public Service Identities within the received ‘WildcardPSI’ so that no further checking and matching procedure is required.

Also under this embodiment and now considering the case of anarchitecture with more than one HSS, FIG. 2 illustrates how the routingentity (I-CSCF) firstly interrogates (S-11) a central network entity(SLF) preferably with a Location Info Request (LIR) that includes thegiven Public Service Identity (PSI-id) in order to identify the HSScurrently holding the given Public Service Identity (PSI-id). Thecentral network entity (SLF) returns (S-12) an indication to redirectthe service invocation towards an indicated HSS (HSS-id), preferablywith a Location Info Answer (LIA). Then, the procedure goes on asdescribed above under the sequence illustrated in FIG. 1.

A second embodiment of the invention illustrated in FIG. 3, shows howfurther service invocations (S-10) with Public Service Identities(PSI-id-2) other than the previously given Public Service Identity(PSI-id) may be treated in accordance with the invention when the otherPublic Service Identities (PSI-id-2) belong to the same ‘Wildcard PSI’range as the previously given Public Service Identity (PSI-id). Underthis second embodiment, the routing of a service invocation merelyrequires one checking procedure (P-11) to determine in the HSS, uponinterrogation (S-13) from the routing entity (I-CSCF), that the‘Wildcard PSI’, which the currently given Public Service Identity(PSI-id-2) belongs to, had been previously assigned an identifier(S-CSCF-id) of the serving entity (S-CSCF) currently handling all PublicService Identities belonging to the ‘Wildcard PSI’.

In this situation, the HSS may answer (S-30) to the routing entity(I-CSCF) with the identifier (S-CSCF-id) of the serving entity (S-CSCF)already assigned for handling all Public Service Identities belonging tothe ‘Wildcard PSI’, as the currently given Public Service Identity(PSI-id-2) does, along with said ‘Wildcard PSI’. The routing entity doesnot need to select a serving entity, and simply forwards (S-21) theservice invocation (INVITE) towards the assigned serving entity (S-CSCF)with the currently given Public Service Identity (PSI-id-2) and the‘Wildcard PSI’, which said currently given Public Service Identitybelongs to.

The serving entity (S-CSCF) receiving (S-21) this invocation finds thatthe given ‘Wildcard PSI’ is known therein, and the serving entity hadalready got a common service profile to be applied for all the PublicService Identities belonging to said ‘Wildcard PSI’, so that the servingentity requires neither being assigned at the HSS to the currently givenPublic Service Identity (PSI-id-2) nor obtaining from the HSS anindividual service profile for the latter. Then, the serving entity(S-CSCF) gets from the previously stored common service profileassociated with the received ‘Wildcard PSI’ an identifier of anApplication Server (AS) where a service identified by the given PublicService Identity (PSI-id-2) is executed, and eventually forwards (S-23)the service invocation (INVITE) to said Application Server (AS)including the received ‘Wildcard PSI’.

Also under this second embodiment, the Application Server (AS) receivingthe ‘Wildcard PSI’ may, depending on particular criteria andimplementation options, apply unique service logic for all PublicService Identities within the received ‘Wildcard PSI’ so that no furtherchecking and matching procedure is required.

As for the first embodiment, this second embodiment is also applicableto an IMS network with more than one HSS, as illustrated in FIG. 4,wherein the routing entity (I-CSCF) firstly interrogates (S-11) acentral network entity (SLF), preferably with a Location Info Request(LIR), the interrogation including the currently given Public ServiceIdentity (PSI-id-2) in order to identify the HSS holding said PublicService Identity (PSI-id-2). The central network entity (SLF) returns(S-12) an indication to redirect the service invocation towards anindicated HSS (HSS-id), preferably with a Location Info Answer (LIA).Then, the procedure goes on as described above under the sequenceillustrated in FIG. 3.

A third embodiment of the invention, as FIG. 5 illustrates, isespecially advantageous for networks with more than one HSS. Under thisthird embodiment an invocation (INVITE) of service identified by a givenPublic Service Identity (PSI-id) is received (S-10) at a routing entityof the IMS network, as an Interrogating Call Session Control Function(I-CSCF) may be, from an access entity such as a Proxy Call SessionControl Function (P-CSCF) where a user accesses the IMS network through.The routing entity (I-CSCF) firstly determines which is the HSS incharge of said given Public Service Identity (PSI-id) by interrogating(S-11) a central network entity (SLF) with the given Public ServiceIdentity (PSI-id), the interrogation being preferably a Location InfoRequest (LIR).

The central network entity (SLF) carries out a checking procedure anddetermines that the given Public Service Identity (PSI-id) matches(P-10) within a ‘Wildcard PSI’ range defined in the central entity asheld by a certain HSS. The central entity (SLF), in accordance with anaspect of the invention, returns (S-40) towards the routing entity(I-CSCF) an indication to redirect the service invocation towards anindicated HSS, an identifier of said HSS (HSS-id), and including the‘Wildcard PSI’. This submission preferably done with a Location InfoAnswer (LIA).

The routing entity (I-CSCF) then interrogates (S-41) the indicated HSS,preferably with a Location Info Request (LIR), and including the givenPublic Service Identity (PSI-id) and the received ‘Wildcard PSI’.

The HSS receiving an interrogation that includes a ‘Wildcard PSI’ doesnot need a complete checking procedure to match a received PublicService Identity but simply determine whether a serving entity (S-CSCF)had been already assigned to said ‘Wildcard PSI’. Provided that theserving entity (S-CSCF) had been already assigned for handling allPublic Service Identities belonging to the ‘Wildcard PSI’, an identifier(S-CSCF-id) of the assigned serving entity along with the ‘Wildcard PSI’is sent back (S-30) to the routing entity (I-CSCF).

The routing entity (I-CSCF) forwards (S-21) the service invocation(INVITE) towards the assigned serving entity (S-CSCF) with the givenPublic Service Identity (PSI-id) and the ‘Wildcard PSI’. The servingentity (S-CSCF) receiving (S-21) this invocation finds that the given‘Wildcard PSI’ is already associated at the serving entity with a commonservice profile to be applied for all the Public Service Identitiesbelonging to said ‘Wildcard PSI’. The serving entity (S-CSCF) does notneed to be assigned at the HSS for given Public Service Identity(PSI-id), and does not need to obtain from the HSS an individual serviceprofile for the latter. Then, the serving entity (S-CSCF) gets from thecommon service profile, which is associated with the received ‘WildcardPSI’, an identifier of an Application Server (AS) where a serviceidentified by the given Public Service Identity (PSI-id) is executed,and eventually forwards (S-23) the service invocation (INVITE) to saidApplication Server (AS) including the received ‘Wildcard PSI’.

Also under this third embodiment illustrated in FIG. 5, the ApplicationServer (AS) receiving the ‘Wildcard PSI’ may, depending on particularcriteria and implementation options, apply unique service logic for allPublic Service Identities within the received ‘Wildcard PSI’ so that nofurther checking and matching procedure is required.

Moreover, as shown at least in the embodiments of FIGS. 3 and 5 andirrespective of having just one or more than one HSS, there is no needfor carrying out more than once checking procedures to match a givenPublic Service Identity (PSI-id; PSI-id-2) received in a serviceinvocation (INVITE) with those defined in a network entity (SLF, HSS,AS), the latter being held as a ‘Distinct PSI’ or as a ‘Wildcard PSI’.

A still further enhancement may be obtained by combining the teaching ofthe second embodiment shown in FIG. 4 with the third embodiment shown inFIG. 5. Thus, in accordance with a fourth embodiment illustrated in FIG.6, the central entity (SLF) interrogated (S-11) about the HSS holding agiven Public Service Identity (PSI-id) may return (S-40) towards therouting entity (I-CSCF) an indication to redirect the service invocationtowards an indicated HSS, an identifier of said HSS (HSS-id), andincluding the ‘Wildcard PSI’ (Wildcard-PSI-a) which the given PublicService Identity (PSI-id). This submission preferably done, as suggestedabove, with a Location Info Answer (LIA). The routing entity (I-CSCF)then interrogates (S-41) the indicated HSS, preferably with a LocationInfo Request (LIR), and including the given Public Service Identity(PSI-id) and the received ‘Wildcard PSI’ (‘Wildcard-PSI-a’).

The HSS receiving such interrogation that includes a first ‘WildcardPSI’ (‘Wildcard PSI-a’) may, nevertheless, carry out a checkingprocedure (P-11) to match the received first ‘Wildcard PSI’ (‘WildcardPSI-a’), and may determine as a result of this checking procedure (P-11)a second ‘Wildcard PSI’ (‘Wildcard PSI-b’) range, which the receivedfirst ‘Wildcard PSI’ (‘Wildcard PSI-a’) belongs to, or is included in,the received first ‘Wildcard PSI’ (‘Wildcard PSI-a’) range.

That is, the second ‘Wildcard PSI’ (‘Wildcard PSI-b’) may be defined atthe HSS as a sub-range of the received first ‘Wildcard PSI’ (‘WildcardPSI-a’), and obtained as a result of also applying the checkingprocedure to match the given Public Service Identity (PSI-id) incombination with the received first ‘Wildcard PSI’ (‘Wildcard PSI-b’),or the second ‘Wildcard PSI’ (‘Wildcard PSI-b’) may be defined at theHSS as a range that includes a sub-range represented by the receivedfirst ‘Wildcard PSI’ (‘Wildcard PSI-a’).

Once said second ‘Wildcard PSI’ (‘Wildcard PSI-b’) has been determined(P-11) at the HSS, the HSS determines whether a serving entity (S-CSCF)had been already assigned to the second ‘Wildcard PSI’ (‘WildcardPSI-b’). Provided that the serving entity (S-CSCF) had been alreadyassigned for handling all Public Service Identities belonging to thesecond ‘Wildcard PSI’ (‘Wildcard PSI-b’), an identifier (S-CSCF-id) ofthe assigned serving entity along with the second ‘Wildcard PSI’(‘Wildcard PSI-b’) is sent back (S-30) to the routing entity (I-CSCF).The sequence of actions following this may continue in a similar manneras for the embodiment shown in FIG. 4.

This embodiment illustrated in FIG. 6 allows that the distribution of‘Wildcard PSI’ ranges is not necessarily the same at the central networkentity (SLF) than in the HSS. Such flexible distribution also allows amore flexible assignation of an S-CSCF to particular ‘Wildcard PSI’ranges in an HSS, whereas such ranges are included in just one ‘WildcardPSI’ defined as such in the central network entity.

On the other hand, both HSS and serving entity (S-CSCF) are arranged forthe HSS to trigger a profile download towards the serving entity,without any explicit request from the latter but rather due to anychange of contents in a service profile or any change of Public ServiceIdentities defined in the HSS that, irrespective of being defined as a‘Distinct PSI’ or as a ‘Wildcard PSI’, may affect any association in theserving entity between a service profile and a Public Service Identity.

In accordance with a further embodiment of the invention not shown inany drawing, the central network entity (SLF) might also return, upon arouting query based on a given Public Service Identity, an identifier ofthe Application Server where the service identified by the given PublicService Identity is executed. This identifier of the Application Servermight also be submitted, directly or indirectly and upon definition oramendment, towards the HSS, or towards any serving entity (S-CSCF) inthe network.

The central network entity, under any of the above embodiments, may be acentralized entity in a network with more than one HSS, the centralentity carrying out a subscription locator function, that is, informingabout the HSS in charge of a given subscription. In this case, thecentral entity may have as well means for answering a routing query fora given Public User Identity with an identifier of a Home SubscriberServer (HSS-id) holding the subscription for the corresponding user.

In a similar embodiment, and for networks configured to allow a directrouting from the routing entity (I-CSCF) to the Application Server, theHSS might return, upon a routing query based on a given Public ServiceIdentity, an identifier of the Application Server where the serviceidentified by the given Public Service Identity is executed, instead ofan identifier of a serving entity (S-CSCF) currently handling theservice invocation.

The invention is described above in respect of several embodiments in anillustrative and non-restrictive manner. Obviously, variations, andcombinations of these embodiments are possible in light of the aboveteachings, and any modification of the embodiments that fall within thescope of the claims is intended to be included therein.

The invention claimed is:
 1. A method for invoking a service identifiedby a Public Service Identity (PSI) in a network, the service beinghandled by a serving entity and the Public Service Identity (PSI) beingheld at a Home Subscriber Server, the method comprising the steps of:receiving an invocation of a service identified by a Public ServiceIdentity (PSI) at a routing entity; interrogating the Home SubscriberServer holding the PSI about a serving entity assignable for handlingthe PSI; forwarding the received invocation of service towards theassignable serving entity; answering the interrogation with anidentifier of a Wildcard PSI range which the PSI belongs to; forwardingthe identifier of the Wildcard PSI range towards the assignable servingentity; assigning at the Home Subscriber Server a common service profileto the Wildcard PSI range to be applicable for Public Service Identitiesincluded in the Wildcard PSI range; and providing the common serviceprofile associated with the Wildcard PSI range to the serving entity,upon receipt of an indication from the serving entity of currentlyholding the Wildcard PSI range.
 2. The method of claim 1, furthercomprising a step of interrogating a central entity about the HomeSubscriber Server holding the PSI in networks with more than one HomeSubscriber Server; and a step of receiving an identifier of the HomeSubscriber Server.
 3. The method of claim 2, further comprising a stepof receiving from the central entity an identifier of a further WildcardPSI range, to which the PSI belongs.
 4. The method of claim 3, whereinthe step of interrogating the Home Subscriber Server about the servingentity comprises a step of forwarding the identifier of the furtherWildcard PSI range received from the central entity.
 5. The method ofclaim 4, wherein the step of answering the interrogation with theidentifier of the Wildcard PSI range, from the Home Subscriber Server,includes a step of matching the further Wildcard PSI range as asub-range of the Wildcard PSI range, the identifier of which is to bereturned with the answer.
 6. A method for invoking a service identifiedby a Public Service Identity in a network, the service being handled bya serving entity and the Public Service Identity being held at a HomeSubscriber Server, the method comprising the steps of: receiving aninvocation of a service identified by a Public Service Identity (PSI) ata routing entity; the routing entity interrogating the Home SubscriberServer, which holds the PSI, about a serving entity assignable forhandling the PSI; the Home Subscriber Server answering to the routingentity either with an identifier of a serving entity already assignedfor the PSI, or with capabilities required for selecting the servingentity, and including in the response an identifier of a Wildcard PSIrange, to which the PSI belongs; forwarding from the routing entity thereceived invocation of service and the identifier of the Wildcard PSIrange towards the assignable serving entity; assigning at the HomeSubscriber Server a common service profile to the Wildcard PSI range,the common service profile to be applicable for Public ServiceIdentities included in the Wildcard PSI range; and providing the commonservice profile associated with the Wildcard PSI range, from the HomeSubscriber Server to the serving entity, upon receipt of an indicationfrom the serving entity of being currently holding the Wildcard PSIrange.
 7. The method of claim 6, further comprising a step of therouting entity interrogating a central entity about the Home SubscriberServer holding the PSI in networks with more than one Home SubscriberServer; and a step of receiving an identifier of the Home SubscriberServer.
 8. The method of claim 7, further comprising a step of receivingat the routing entity from the central entity an identifier of a furtherWildcard PSI range, which the PSI belongs to.
 9. The method of claim 8,wherein the step of the routing entity interrogating the Home SubscriberServer about the serving entity comprises a step of forwarding from therouting entity the identifier of the further Wildcard PSI range towardsthe Home Subscriber Server.
 10. The method of claim 9, wherein the stepof the Home Subscriber Server answering the interrogation with theidentifier of the Wildcard PSI range includes a step of matching thefurther Wildcard PSI range as a sub-range of the Wildcard PSI range, theidentifier of which is to be returned with the answer.
 11. A system forinvoking a service identified by a Public Service Identity (PSI) in anetwork, the service being handled by a serving entity and the PSI beingheld at a Home Subscriber Server, the system comprising: a routingentity configured to receive an invocation of a service identified by aPublic Service Identity (PSI); a Home Subscriber Server holding the PSI;and a serving entity assignable for handling a service identified by thePSI; the routing entity being further configured to: interrogate theHome Subscriber Server holding the PSI about the serving entityassignable for handling the service identified by the PSI; receive fromthe Home Subscriber Server an identifier of a Wildcard PSI range whichthe PSI belongs to; and forward the received invocation of service andthe identifier of the Wildcard PSI range towards the assignable servingentity; the Home Subscriber Server being configured to: submit to therouting entity the identifier of the Wildcard PSI range which the PSIbelongs to; assign a common service profile to the Wildcard PSI range,the common service profile to be applicable for Public ServiceIdentities included in the Wildcard PSI range; and provide the commonservice profile associated with the Wildcard PSI range to the servingentity, upon receipt of an indication from the serving entity of beingcurrently holding the Wildcard PSI range; and the serving entity beingconfigured to: receive the invocation of the service and the identifierof the Wildcard PSI range forwarded from the routing entity; submit theindication of being currently holding the Wildcard PSI range to the HomeSubscriber Server; and receive from the Home Subscriber Server thecommon service profile associated with the Wildcard PSI range.
 12. Thesystem of claim 11, wherein the routing entity is further configured to:interrogate a central entity about the Home Subscriber Server holdingthe PSI, in networks with more than one Home Subscriber Server; andreceive an identifier of the Home Subscriber Server holding the PSI. 13.The system of claim 12, wherein the routing entity is further configuredto receive from the central entity an identifier of a further WildcardPSI range, to which the PSI belongs.
 14. The system of claim 13, whereinthe routing entity is further configured to forward the identifier ofthe further Wildcard PSI range received from the central entity towardsthe Home Subscriber Server.
 15. The system of claim 14, wherein the HomeSubscriber Server is further configured to: match the further WildcardPSI range as a sub-range of the Wildcard PSI range; and submit theidentifier of the Wildcard PSI range to the routing entity.